1. Field of the Invention
The present invention relates to a nitride type compound semiconductor light emitting element (laser and light emitting diode) that can produce light emission in the region from blue light to ultraviolet. In particular, the present invention relates to a white light or multi-color light emitting element having a phosphor formed in a nitride type compound semiconductor light emitting element.
2. Description of the Background Art
As a conventional example of a light emitting diode, FIG. 18 shows a structure of a nitride gallium type compound semiconductor light emitting element 400 converting the wavelength of light from a light emitting layer to obtain light differing in wavelength from the light emitting wavelength. A light emitting chip 100 is disposed at a bottom 300 of a cup. A mold resin 200 including a wavelength converting material (fluorescent material) is formed around light emitting chip 100. The wavelength of the light emitted from light emitting chip 100 is converted. Such a light emitting diode is disclosed in, for example, Japanese Patent Laying-Open No. 7-99345.
The above conventional light emitting diode had problems set forth below. When a wavelength converting material (fluorescent material) is included in the mold resin, there is a change in the optical characteristics due to the fluorescent material being provided unevenly in the mold resin. There was also a significant variation in the characteristics if the amount of the mold resin slightly changes. The conventional light emitting chip could not convert the wavelength of the emitted light into a different wavelength unless a mold resin containing fluorescent material was formed at the outer side or around the light emitting chip. There was a problem that the wavelength of the emitted light could not be converted into a different wavelength by the light emitting chip per se.
An object of the present invention is to provide a nitride type compound semiconductor light emitting element having the aforementioned problem solved.
According to an aspect of the present invention, a nitride type compound semiconductor light emitting element has a multilayer structure including a substrate, a nitride gallium type compound semiconductor layer of a first conductivity type, a nitride gallium type compound semiconductor light emitting layer, and a nitride gallium type compound semiconductor layer of a second conductivity type. In the nitride type compound semiconductor light emitting element, a phosphor is provided in the multilayer structure or at a portion of the substrate. This allows the emitted light to be converted in wavelength by the light emitting diode alone.
In the nitride type compound semiconductor light emitting element of the present invention, the phosphor is coated with a transparent conductor film at its surface.
In the nitride type compound semiconductor light emitting element of the present invention, the phosphor is formed below the nitride gallium type compound semiconductor light emitting layer.
In the nitride type compound semiconductor light emitting element of the present invention, the phosphor is formed in the substrate.
In the nitride type compound semiconductor light emitting element of the present invention, the phosphor is formed at at least two sites in the direction where the layers are stacked.
In the nitride type compound semiconductor light emitting element of the present invention, the multilayer structure has a highly-reflective layer formed at at least one side.
In the nitride type compound semiconductor light emitting element of the present invention, the highly-reflective layer is also formed at opposite sides.
In the nitride type compound semiconductor light emitting element of the present invention, the highly-reflective layer is also formed at the bottom plane of the substrate.
In the nitride type compound semiconductor light emitting element of the present invention, the phosphor is formed of at least two types of phosphors.
In the nitride type compound semiconductor light emitting element of the present invention, the transparent conductor film is formed of at least one of In2O3, SnO2 and ZnO, or a mixture thereof